Yamato

The Yamato is Vergil's trademark dark-forged blade appearing in Devil May Cry, Devil May Cry 3, and Devil May Cry 4. It is a legendary sword that was once wielded by his father, Sparda, and was left to Vergil as a keepsake.

Description
Yamato is a katana with an ornate bronze guard; the exact details of how it looks change throughout the series. In the first Devil May Cry the Tsuka (柄) has the traditional gold wrapping, with black ornaments, and the Tsuba (鍔) is octagonal. In later installments, the guard is an oval, and the tsuka-ito seems to be braided from white and black material. The blade features several intricate ornaments, most notable is a relief of a dragon at the endpoint of the hilt. The inside and back of Nero's Devil Bringer mimics the design of the blade's hilt.

The scabbard is black, made of traditional lacquered wood, and features several metallic ornaments on its far end. In Devil May Cry 3 it also features a yellow sageo, the cord used to tie the katana to the waist.

When in Devil Trigger, the scabbard changes and looks like an Indonesian traditional dagger, Kris's sheath. It also sticks on Vergil's left arm.

Despite having a scabbard, Yamato is only occasionally worn on the waist—Vergil and Dante carry it in their hands during battle (though Vergil has been shown to carry it on his waist when not in use, such as when wielding a different weapon or using both of his hands for another task), Nero carries it sheathed in his Devil Bringer, and Sparda carries it strapped to his back.

Powers
Although Yamato resembles a katana, it is said to be able to cut through anything, as it is even sharper than the Japanese blade, and is imbued with tremendous magic. In fact, this is the only thing shown to be capable of damaging the otherwise invulnerable Devil Bringer.

Vergil swings the sword so fast that Yamato doesn't appear to even leave its sheath. The ability is capable of hitting any enemies that are within the rather large distortion radius.

Dante attempts to imitate this move in Devil May Cry 4 and the result is a similar ability called Slash Dimension but it lacks the precision and potency of Judgement Cut due to Dante inexperience with wielding Yamato unlike Vergil. Both abilities are able to strike far away opponents. Dante and Vergil demonstrate Yamato's ability to cut far away enemies with normal swings as well. Vergil, during Dante's battle with Arkham where Vergil appears and slices Arkham's hand off from atop a pillar a good distance away, and Dante, when he uses it to destroy the Hellgate with a single swing from a great distance away in Devil May Cry 4.

Similar to the Sword of Sparda before it, Yamato was used to seal a pathway to the Demon World—in this case the Hell Gate on Fortuna. The gate is reopened by the Order of the Sword using Yamato, but later destroyed by Dante, using the same blade.

Story
Yamato once belonged to Vergil's father, Sparda, and according to the Order of the Sword, it was used to seal the "true Hell Gate". It was eventually given to Vergil as a memento, and he used it as his primary weapon.

Vergil uses Yamato as his primary weapon while attempting to reactivate the Temen-ni-gru. When his attempt fails, Vergil and his Yamato fall into the Demon World, where he is found by Mundus. Vergil attempts to defeat the demon king like his father, but is defeated and reborn as Nelo Angelo, presumably along with his blade.

At some later point, Yamato was found, shattered, by the Order of the Sword. It was kept in Agnus's Containment Room within Fortuna Castle, but is restored and taken by Nero when his dormant powers as an heir to Sparda emerge, and thereafter, Nero is able to use the sword while in Devil Trigger. However, it is taken back from him by Sanctus when he is absorbed into the Savior, and is then used by Agnus to reopen the Hell Gate. After slaying Agnus, Dante retrieves Yamato from the gate seal and uses it to destroy the gate, after which he wields it while in his Dark Slayer Style. While fighting the Savior, Dante uses the blade to free Nero, and sends it back to him so that the youth can finish the fight against Sanctus. After the battle, Dante charges Nero with keeping it.

Gameplay
Although Yamato is said to be able to cut through anything, this aspect does not carry through to gameplay for obvious reasons. Enemies with shields, such as Dullahans, are still invulnerable, and background objects are not affected.

Dark Slayer Style
Yamato is intimately linked to Vergil's signature Dark Slayer Style, which he uses in Devil May Cry 3: Special Edition and which Dante homages in Devil May Cry 4. As a warrior fallen from grace, Vergil can use the power of darkness to obtain new weapons and skills by leveling the style, and it interacts with his Yamato, Summoned Swords, Beowulf, and Force Edge. The style itself performs much like Dante's Trickster Style. In Devil May Cry 4, Dante obtains this style after receiving Yamato, but instead of being based on teleportation, it allows Dante to imitate Vergil's skills with Yamato.

Devil May Cry
In Devil May Cry, Yamato replaces the Force Edge for Dante's "Legendary Dark Knight" costume. It behaves exactly the same as the Alastor, even to the point that Sparda carries it on his back when not in use and wields it as a broadsword rather than using the Iaido technique. When Sparda enters Devil Trigger, Yamato transforms into the Sparda sword.

Devil May Cry 3
Vergil is the only character to use Yamato in Devil May Cry 3: Special Edition. When Vergil fights with Yamato, he uses both the scabbard and the blade in the Iaido style. When the Force Edge is equipped, Vergil fights with the Force Edge in place of the Yamato's scabbard. For Vergil's "Corrupt Vergil" or "Super Corrupt Vergil" costumes, Yamato transforms into Nelo Angelo's zweihänder when in Devil Trigger. This may also be related to how Yamato was broken between Devil May Cry 3 and Devil May Cry 4.

Devil May Cry 4
Both Dante and Nero wield Yamato in Devil May Cry 4. Nero's use of Yamato is limited to when he is in Devil Trigger, and even then he only has a few attacks with it. While in Devil Trigger, Yamato also grants Nero the ability to use Summoned Swords. In contrast to Vergil and Dante's use of the Iaido technique, Nero wields Yamato without its scabbard.

When Dante obtains Yamato, he gains access to Vergil's signature Dark Slayer Style.

Devil May Cry 3
It is worth noting, that after executing Yamato Combo, Upper Slash or Force Edge Combo, if Vergil is able to successfully complete the sheathing animation, he will gain a Devil Trigger Orb and a small increase to Style points as well.
 * Vergil's Devil Arm

Also, performing a taunt with Yamato equipped, while there are enemies around, will cause Vergil to emit a black aura after a few seconds, that will replenish his Devil Trigger gauge on its own, as long as he is unharmed and stays in the taunting stance.

Devil May Cry 4

 * Nero's Devil Arm
 * Dante (DarkSlayer)
 * Vergil's Devil Arm

Background
(大和) is a Japanese term referring to the people and traditional nationalistic spirit of Japan, and in the past to the nation itself. Thus, it is appropriate as the name of the weapon symbolizing Vergil's personal aesthetic and commitment to tradition and power, as opposed to Dante's personality of resistance symbolized by the Rebellion, though the kanji are different (閻魔刀).

Trivia

 * In Devil May Cry 4, Dante is shown with both Yamato and its scabbard as he destroys the Hell gate, despite the scabbard not being seen to be retrieved by Nero, or carried by Sanctus or Agnus. When he returns Yamato to Nero, the scabbard disappears once more until Nero offers to return it. Additionally, this scabbard is different from the one seen in previous games, as there are no sageo or gold ornate designs.
 * The damage caused by Yamato generally does not become apparent until the sword is resheathed, although this seems to be a stylistic choice as resheathing the blade isn't a necessary action whenever damage is dealt in gameplay.
 * It's quite possible that Yamato was transformed into the huge sword wielded by Nelo Angelo, if this is the case it would explain how Yamato appears broken and damaged when first seen in Devil May Cry 4. 
 * Dante's sword, Rebellion, is the only object that has been shown to successfully stop a full strength swing from Yamato. This is something that even Nero's Devil Bringer was not capable of despite being invulnerable to damage from Rebellion. Although a weakened Vergil's strike was stopped by the relatively mundane metal barrel of Kalina Ann, and later by Jester's bare hands.

Wielders
Throughout the course of Devil May Cry, Yamato only had four wielders. The first being Sparda, the second being Vergil, the third being Dante and the fourth and current being Nero.